Energy harvesting has been around for many years in the form of windmills and watermills. Modern technology has transformed them into wind turbines, hydro-electric plants, and solar panel arrays. These methods of harvesting energy offers two significant advantages over battery powered solutions: virtually inexhaustible resources and little or no adverse environmental effects.
However, the various technologies used in large scale energy harvesting all require a connection to the power grid. Given the trend towards wireless systems, the continuously powered device which never needs to be recharged by connecting to the power grid is the ultimate goal. While ultra-low-power technology is developing, current radiation harvesting devices are very limited. The traditional crystalline silicon, cadmium telluride, and copper indium gallium selenide solar cells only provide power during the daytime. None of the current solutions can provide continuous, around the clock energy harvesting.